A comprehensive model of the binocular processing mechanisms in normal vision is an essential prerequisite to understanding binocular visual disorders. The goal of this proposal is thus to determine the number and form of the mechanisms involved in binocular and stereoscopic processing. The significance of this goal is to provide a basis from which to evaluate disorders of human binocular vision including strabismus, optical imbalances and the effects of monocular retinal disturbances. How the binocular sensory processing is affected by these problems and to what degree it recovers from them is determined by the mechanisms of binocular processing. A full study of the structure of human stereopsis will be conducted to determine the organization of both spatial channels and binocular disparity channels for stereopsis. The stimuli will be designed to be restricted to local regions on the dimensions of eccentricity, spatial frequency and disparity, to control for interactions between these dimensions. This study can estimate how many separate neural mechanisms make up the input for stereopsis under a full range of stimulus conditions. A similar analysis will be conducted with stimuli designed to isolate the processes of perceptual depth reconstruction, to determine whether there is a multichannel structure for human depth perception.